Metal Ceramic Chassis for Portable Devices

ABSTRACT

An information handling system chassis is built at least in part from ceramic elements. For example, a transparent aluminum oxide ceramic portion covers a touchscreen to provide a rigid outer surface for accepting end user inputs. As another example, a ceramic chassis element has a ceramic material formed around a metal material of similar substance with bonding of the ceramic to the underlying material enhanced with oxidation of the outer surface of the metal material.

CROSS REFERENCE TO RELATED APPLICATIONS

U.S. patent application Ser. No. 13/671,263, entitled “InformationHandling System Ceramic Chassis,” inventors Nicholas D. Abbatiello andDeeder M. Aurongzeb, Attorney Docket No. DC-100341.01, filed on same dayherewith, describes exemplary methods and systems and is incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to the field of informationhandling system chassis, and more particularly to a metal ceramicchassis for portable devices.

2. Description of the Related Art

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option available to users is information handling systems. Aninformation handling system generally processes, compiles, stores,and/or communicates information or data for business, personal, or otherpurposes thereby allowing users to take advantage of the value of theinformation. Because technology and information handling needs andrequirements vary between different users or applications, informationhandling systems may also vary regarding what information is handled,how the information is handled, how much information is processed,stored, or communicated, and how quickly and efficiently the informationmay be processed, stored, or communicated. The variations in informationhandling systems allow for information handling systems to be general orconfigured for a specific user or specific use such as financialtransaction processing, airline reservations, enterprise data storage,or global communications. In addition, information handling systems mayinclude a variety of hardware and software components that may beconfigured to process, store, and communicate information and mayinclude one or more computer systems, data storage systems, andnetworking systems.

Information handling systems have tended over time to increase theirprocessing and storage capabilities even while decreasing theirfootprint. For example, ultra-lightweight laptop and tablet informationhandling systems support many advanced functions in extremely portablechassis. One difficulty with such lightweight chassis is that structuralelements of the chassis tend to have less strength and robustness due tothe less-substantial size and thickness of material used to build thestructural elements so that weight is decreased. For example, tabletinformation handling systems typically have touchscreen displays thataccept inputs made as gestures at the touchscreen. Lightweight chassisfor supporting touchscreens tend to have reduced rigidity so thattouches cause oscillation at chassis structural elements. Plasticcomponents offer light weight, but tend to lack the strength to stand upto normal use. Metal and carbon fiber components can interfere withwireless communications, often do not offer favorable aesthetics andtend to impact recyclability of a system. Yet, chassis structuralelements that have too great of rigidity are at risk of rupture in theevent of too great a deflection.

SUMMARY OF THE INVENTION

Therefore a need has arisen for a system and method which supportsinformation handling system components in chassis with ceramic elements.

In accordance with the present invention, a system and method areprovided which substantially reduce the disadvantages and problemsassociated with previous methods and systems for supporting informationhandling system components in a chassis. Ceramic materials are used tobuild chassis elements that are assembled into an information handlingsystem chassis. Various chassis elements used to assemble a chassis havevarious ceramic materials for providing desired color, transparency,ductility and hardness. For example, oxide and nitride ceramics heatedin varying manners provide different ductility to support functions ofdifferent portions of an information handling system, such supportinginputs through a ceramic touchscreen or supporting processing componentsin a ceramic base. A chassis element may be formed with layers ofdifferent ceramic and metal materials to provide tailored structural andaesthetic characteristics. The metal base specifically important whenthe thickness of the base is <1 mm. To reduce stress and deflection inceramic chassis low density metal plate is critical to support ceramicstructure.

More specifically, an information handling system processes informationwith a processor and memory disposed in a chassis assembled from ceramicchassis elements. In various embodiments, the chassis elements are builtof various ceramic materials formed with various manufacture techniquesto provide targeted material characteristics in support of informationhandling system functions. For instance, a display cover has arelatively rigid and transparent ceramic material to allow interactionby an end user with a touchscreen display through the ceramic materialwithout introducing excessive oscillations. A ceramic bezel having arelatively high degree of ductility couples to a ceramic chassis basehaving a relatively low degree of ductility. In some alternativeembodiments, multi-layer ceramic chassis elements have layers of ceramicmaterials and/or metal materials in which different layers havedifferent levels of ductility. Ceramic chassis elements are formed froma ceramic mixture, such as a ceramic base of alumina, having a stiffenerthat makes the mixture suitable as an injection molding feedstock.Coupling devices are integrated in the ceramic material before sinteringso that sintering causes densification of the ceramic material andcoupling device into an integrated chassis element. Aesthetic appearanceis provided by adding a dopant to the ceramic mixture or treating theceramic after sintering. In order to provide a uniform appearance, metalchassis elements are coated with a ceramic and annealed to diffuse theceramic material with the underlying metal material.

The present invention provides a number of important technicaladvantages. One example of an important technical advantage is that aninformation handling system chassis is assembled from ceramic and othermaterials to provide tailored functionality with ceramiccharacteristics. For example, a tablet information handling system has aceramic chassis element base that integrates ceramic coupling devices tosecure processing components in a strong, durable and relatively rigidbase. The tablet has a more ductile ceramic bezel holding the display tothe base to provide greater flexibility in the event of end user impactsto the base. A transparent ceramic cover over the display adapts toaccept end user inputs made to a touchscreen of the display. Ceramicmaterials and coatings provide light weight chassis elements to build aportable information handling system that has a tough exterior with adurable finish integrated with the ceramic material, such as with adopant, micro arcing, or deposition of an overlying material.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood, and its numerousobjects, features and advantages made apparent to those skilled in theart by referencing the accompanying drawings. The use of the samereference number throughout the several figures designates a like orsimilar element.

FIG. 1 depicts a blow-up view of a tablet information handling systemdisposed in a chassis having ceramic elements;

FIG. 2 depicts a side perspective view of a tablet information handlingsystem having a chassis with ceramic elements and an open cover;

FIG. 3 depicts a side perspective view of a tablet information handlingsystem having a chassis with ceramic elements and a closing cover;

FIG. 4 depicts a flow diagram for a process of forming a ceramic chassiselement;

FIG. 5 depicts a ceramic chassis element having coupling devices tocouple with information handling system components;

FIG. 6 depicts a flow diagram of a process for integrating a couplingdevice with a ceramic chassis element;

FIG. 7 depicts one embodiment of a multi-layered ceramic chassis elementwith one or more layers having different levels of ductility;

FIG. 8 depicts a flow diagram of a process for forming a ceramic chassiselement with deposition of ceramic material over a metal base;

FIG. 9 depicts an example of motion imparted at a chassis element duringmicro arc deposition to provide a desired surface pattern;

FIG. 10 depicts a functional block diagram of a process for coating abase metal with a dopant to form an oxide surface coating; and

FIG. 11 depicts a ceramic plate for assembly into a mounting frame tomake an information handling system chassis.

DETAILED DESCRIPTION

Ceramic chassis elements support information handling system componentswith desired rigidity and aesthetics. For purposes of this disclosure,an information handling system may include any instrumentality oraggregate of instrumentalities operable to compute, classify, process,transmit, receive, retrieve, originate, switch, store, display,manifest, detect, record, reproduce, handle, or utilize any form ofinformation, intelligence, or data for business, scientific, control, orother purposes. For example, an information handling system may be apersonal computer, a network storage device, or any other suitabledevice and may vary in size, shape, performance, functionality, andprice. The information handling system may include random access memory(RAM), one or more processing resources such as a central processingunit (CPU) or hardware or software control logic, ROM, and/or othertypes of nonvolatile memory. Additional components of the informationhandling system may include one or more disk drives, one or more networkports for communicating with external devices as well as various inputand output (I/O) devices, such as a keyboard, a mouse, and a videodisplay. The information handling system may also include one or morebuses operable to transmit communications between the various hardwarecomponents.

Referring now to FIG. 1, a blow-up view depicts a tablet informationhandling system 10 disposed in a chassis 12 having ceramic elements,such as a base 14, a cover 16 and a bezel 18. A motherboard 20 couplesto ceramic coupling devices 22 integrated with ceramic base 14 andsupports communication between various processing components thatcooperate to process information, such as a CPU 24 that executesinstructions, RAM 26 that stores instructions, a chipset 28 thatcoordinates interactions between processing components and solid statedrive 30 that provides persistent storage of instructions. Chipset 28includes graphics processing capabilities that process information togenerate information for presentation at display 32. Display 32 has atouchscreen that accepts end user touches and inputs and provides theinputs to chipset 28 for use by CPU 24. Bezel 18 is a ceramic elementthat couples display 32 in place over base 14 in a tablet configuration.Cover 16 is a transparent ceramic element that protects display 32.Ceramic elements 14, 16 and 18 assemble to provide a chassis withmultifunctional ceramic materials that can embed sensors for an improveduser experience. Chassis 12 in general and some ceramic elements inparticular have two or more layers with the layers having differentductile characteristics. For example, a structure of two or more layersmay include an insert molded or bonded metal plate placed diagonally orin other orientations, which is thinner than ceramic layers. Althoughthe ceramic elements depicted by the example embodiment of FIG. 1assemble to form a tablet configuration, other configurations ofinformation handling systems may be used, such as mobile telephone,clamshell and desktop configurations.

Referring now to FIG. 2, a side perspective view depicts a tabletinformation handling system 10 having a chassis 12 with ceramic elementsand an open rotating cover 34. Ceramic elements used to assemble chassis12 provide various ductile characteristics to support informationprocessing functions and end user interactions. For example, base 14 hasa high stiffness to provide adequate support for processing componentsdisposed within base 14, such as by limiting movement relative at amotherboard so that electrical connections do not suffer stress orbreak. Bezel 18 has a lower stiffness than base 14 to absorb some energyfrom end user interactions. Cover 16 is a functional sensor ceramic thatprovides high rigidity to reduce oscillations introduced by end userinputs to the touchscreen. In one embodiment, cover 16 includespersistent ceramic inclusions that provide light emissions after thedisplay is powered down, such as a red glow. Rotating cover 34 providesa transparent glass ceramic material to protect cover 16 when an enduser does not need access to the touchscreen.

Referring now to FIG. 3, a side perspective view depicts a tabletinformation handling system having a chassis with ceramic elements and aclosing rotating ceramic cover 34. Rotating ceramic cover 34 hasintegrated ceramic hinges 36 that couple to chassis 12. Combiningceramic elements having different ductile characteristics allowstailoring of chassis 12 to address component breakage, heat conductivityand EMC characteristics, such as by layering individual ceramic elementswith metal inserts. Ceramic manufacturing by injection molding,deposition or other techniques to have a metal based ceramic with thesame element as a metal insert provides a stable material for longlasting chassis life. The ceramic elements are built from oxide ornitride materials, such as Al2O3, MgO, HfO, LuO and Si oxide or Oxynidein the access of >70% and a 10% of Y,V oxide. Additional dopant in theaccess of 5% Ni, Ti, Co, Cr, and/or Zn is used to get desired color andoptical properties. To support forming a desired chassis element shapewith a press and mold technique, a polymer and nano clay are added inaccess of >5%, thus allowing the material to hold its shape after apress and mold. Nano clays are commercially available nanoparticles oflayered mineral silicates that are classified based upon chemicalcomposition and nanoparticle morphology, such as classes ofmontmorillonite, betonies, kaolinite, hectorite and halloysite.Organically-modified nano clays, known as organoclays, are analternative to pure nano clays, which provide an attractive class ofhybrid organic-inorganic nanomaterials with potential use in polymernano composites, such as rheological modifiers, gas absorbents and drugdelivery carriers. In the use of a ceramic chassis element, nano clayprovides a stiffener and Rheological modifier to maintain a desiredshape. The mixture of the ceramic material, dopant, polymer and nanoclay forms a viscous material adapted to injection molding for forming aceramic element chassis shape, such as a chassis portion having athickness of approximately 1mm. After forming the ceramic elementchassis shape, sintering in a hydrogen or argon flow for 5 hours orgreater at a temperature or 1000 degrees Celsius or greater densitiesthe viscous material into a ceramic having desired rigidity.

Referring now to FIG. 4, a flow diagram depicts a process of forming aceramic chassis element. The process starts at step 36 with a mixture ofmaterials to form an injection molding material. For example, a threecomponent powder is mixed having a ceramic main material, a stiffenerand a powder as described with the various material options above. Atstep 38, the ceramic mixture is formed into a chassis element shape,such as with injection molding or by otherwise pressing the ceramicmixture into a tool. At step 40, the chassis element shape is subjectedto high temperature sintering in a desired gas environment, such as aninert gas for greater than 6 hours, in order to densify the ceramicmaterial to obtain desired rigidity. In one embodiment, alumina is usedas the ceramic material and treated to have a transparent qualityadapted to cover a display. As an alternative, at step 42 the sinteredceramic chassis element is coated to provide a desired color, such aswith chemical vapor deposition (CVD) or sputtering at a high substratetemperature. In one embodiment, to obtain a target coating of a bluecolor, electrolytic plasma oxidation is performed on the sinteredceramic chassis element. Cobalt is deposited with E-beam evaporation ina low pressure environment to obtain a thickness or 0.5 micrometers andsubsequently annealed at 700 degrees Celsius or greater in an oxygenatmosphere. In this example embodiment, the cobalt thickness should notexceed 1 micrometer in order to induce oxidation and diffusion. Othermixed-alloy or dip-coating followed by high temperature thermalannealing will also form stable coloration on an oxide ceramic.

Referring now to FIG. 5, a ceramic chassis element 14 is depicted havingcoupling devices 44 to couple with information handling systemcomponents. For example, ceramic chassis element 14 is a plate ofceramic material forming a base of an information handling system. Aceramic plate of approximately 6 to 8 inches in length has insert moldedcoupling device pins 44 with a diameter of approximately 1 mm to hold aframe or other structure, such as a printed circuit board. In oneexample embodiment, the primary ceramic material is alumina with adopant for coloring and the coupling devices 44 are formed from amaterial with a similar coefficient of thermal expansion (CTE), such asniobium having other metal alloys, such as Al, Ir, Ti, or Ni, or anoxide, such as aluminum titante. Other alternative materials forcoupling devices 44 include a high carbon material, aluminum, pureniobium and tungsten. Sintering of a ceramic material that forms chassiselement 14 after insertion of pin 44 results in a formed ceramic elementhaving coupling devices 44 integrated with chassis element 14.

Referring now to FIG. 6, a flow diagram depicts a process forintegrating a coupling device with a ceramic chassis element. Theprocess starts at step 46 by mixing a ceramic powder with a polymer intoa material that will hold a desired chassis element shape, such as withinjection molding or pressing. In one example embodiment, the polymerorganic vehicle includes three constituents: polypropylene grade SA868Mavailable from Taiwan Polypropylene Co; paraffin wax available fromMerck and stearic acid available from Merck. The ceramic material hasparticle distribution of a-alumina of 4 micrometers, available fromSumitomo of Japan. The mixture formulation has 70% by weight of 4micrometer alumina, 10% nano alumina, such as alfa-aeser 100 nm; 5% GrO(graphene oxide); 3% of a pigment ceramic, such as MgO, Cr or Cu; 8%polyethylene glycol, 4% polypropylene, and 1% stearic acid. Mixing ofthe ceramic powder and binder is performed in a Z-type twinscrew blenderat 180 degrees Celsius for 40 minutes. After mixing, the ceramicmaterial is extruded into granules of 2 to 3mm to serve as a feedstockfor injection molding. In alternative embodiments, alternativevariations of the ceramic mixture may be developed as desired to obtaindesired qualities of the ceramic chassis element.

At step 48, the ceramic mixture is formed to a chassis element shapewith injection molding or another appropriate method. In the exampleembodiment, injection molding is performed with an Arburg 270-210-500machine having a barrel temperature of 150 degrees Celsius to feed thenozzle and a mold temperature of 120 degrees Celsius. Initial injectionpressure is set at greater than 1400 bar with a locking force of 300 kN.After the ceramic chassis element is formed with the ceramic mixture,the injection molded part is sintered at various temperatures to densifythe ceramic material for desired ductility; however, before sinteringcoupling devices 44 are insert molded into the ceramic material. At step50, in some embodiments, the location for insert molding and/or thecoupling device is coated with a conductive ceramic paste to foster astrong ceramic bond between coupling device 44 and chassis element 14.At step 52, coupling device 44 is inserted into the ceramic material sothat the material of the coupling device becomes part of the ceramicstructure during the sintering and densification process. At step 54,the ceramic material with the inserted coupling device is sintered at ahigh temperature, such as at 1700 degrees Celsius or greater in a vacuumor environment of 700 torr argon for four hours or greater. Variationsin the temperature and time of sintering provides variations in thecharacteristics of the ceramic material. For example, sintering at 1700degrees Celsius for 12 hours provides a grain size of 150 micrometers+/−20% and a deflection at rupture of 1 mm; sintering at 1600 degreesCelsius for 2 hours provides a grain size of 20micrometers +/−40% and adeflection at rupture of 0.3 mm. At step 56, a planar layer is depositedover the ceramic chassis element for aesthetic or material objectives.For example, AlSiC or AIN deposited over the ceramic chassis elementincreases surface conductivity, such as with sputtering. Other types ofmaterials may be selected based upon CTE or other properties desired forthe chassis. For example, to enhance scratch resistance a titanium basedsurface is formed as a final exposed surface layer, such as titaniumdeposited to form a TiN or TiCN ceramic for an aluminum to titaniumbased ceramic. It should be noted that similarly for coating to bestable the base plate should have at least 1 composition common. Forexample, for TiN or TiCN to be stable during usage condition, base metalcan be alloy but should have Ti in it, for example AlTi alloy. It shouldbe noted that ductility of the ceramic plate can be increased bycon-sintering the mix at >1500C with dispersed alumina fiber. α-Al2O₃fibers with diameters of 300-400 nm were successfully prepared through aconvenient electrospinning combined with sol-gel technology process. Thefibers can also be purchased commercially.

Referring now to FIG. 7, one embodiment is depicted of a multi-layeredceramic chassis element 58 with one or more layers having differentlevels of ductility. Two-layer ceramic chassis element 58 has analuminum titanate base layer 60 and an alumina upper layer with anintermediate titanium plate 64. In one embodiment, chassis element 58 isformed with hot pressed diffusion bonding at approximately 1500 degreesCelsius. In an alternative embodiment, hot pressed diffusion bondingwith a titanium alloy, such as Al, Ir, Ni, Ti, Nb, Mg, V, Ta, or Mobased alloys, having a similar diffusion point of Mania plate 64 isperformed at a lower temperature, such as 1400 degrees Celsius. Notethat melting point can be slightly modulated based on grain size anddensity. This is also true for AlIr, TiIr, NiTi, NbAlTi, and NbAl typealloy. Note that the metal plate can be further coated or doped withother conductive material like Cu or silver. In an alternativeembodiment, multi-stage injection molding forms the piece. The aluminumtitanate base plate 60 may have reinforcement with fiber, such as agraphene oxide fiber, glass fiber, carbide based ceramic fiber or carbonfiber, in order to increase the ductility of the base layer. Inalternative embodiments, titanium plate 64 may be place in varyingorientations, such as lengthwise or diagonally, in order to vary theductility of the overall structure to various anticipated loads. Inanother embodiment, titanium plate 64 has a thickness that is less thanthe thickness of each of the overlying and underlying ceramic plates. Inalternative embodiments, titanium plate 64 may have different types ofsingle metals or alloys chosen to have a stiffness modulus of greaterthan 20 GPa.

Referring now to FIG. 8, a flow diagram depicts a process for forming aceramic chassis element with deposition of ceramic material over a metalbase. A stable oxide ceramic is deposited over a metal chassis portionto provide a look and feel of a ceramic product. For example, the metalchassis portion is formed to a chassis element shape with a low meltingpoint metal, such as a metal having a melting point of less than 2000degrees Celsius. In one embodiment, the ceramic formed over the metalchassis has a metal composition similar to the metal chassis, such as analumina ceramic formed over an aluminum chassis or titanium oxide formedover titanium. Coating of aluminum chassis elements with Al₂O₃ improvesmechanical properties and provides a consistent appearance when chassiselements are assembled into a chassis that includes both metal andceramic portions. Color and optical properties of alumina coatedaluminum may be further adapted to a desired finish by combiningsuitable materials, such as Y2O3, ZrO₂, SiC and TiO₂, with an Al₂O₃—ZrO₂ceramic outer coating providing a desired in finish in one embodiment.Note that after annealing the mixed composition can form likeAl2TiO5—MgTi2O5 solid solution ceramics, i.e. Mg0.5AlTil.5O5 . In thesystem where TiO2 is not used, Yttrium, neodymium and zirconium basedmixed ceramic can form. Based on deposition process and masking grainsize can vary from fibrous and directional to random.

The process begins at step 66 with selection and forming of a substratematerial into a chassis element shape. In the example embodiment,commercial aluminum plate is formed into a desired shape, such as anALOCA 2024 aluminum sheet having a square shape with six inch sides anda thickness of approximately 0.6 mm. At step 68, the surface of thealuminum is prepared for deposition by encouraging oxidation to adesired depth, such as approximately 2 micrometers. In one embodiment,the aluminum plate is heated to 400 degrees Celsius using a radiativeheating element under an oxygen flow. After oxidation of the outersurface, the process continues to step 70 to coat the oxidized surfacewith ceramic material, such as alumina. For example, alumina is sputterdeposited to a thickness of 50 micrometers. Oxidation and sputtering maybe performed on the entire surface or just a portion of the surface thatis exposed after the chassis is assembled. At step 72, the sputteredchassis element is exposed to a high temperature to diffuse the aluminainto the oxidized surface of the sheet metal, such as a temperature of1700 degrees Celsius. At step 74, after diffusion of the alumina intothe oxidized surface, the chassis element is subjected to a lowtemperature annealing, such as 400 degrees Celsius, to provide a desireddiffusive finish. A relatively thin ceramic finish with good diffusionprevents cracking of the ceramic surface. In an alternative embodiment,a magnesium chassis is coated with MgO or MgO+SiO ceramic using thecoating process. In another alternative embodiment, a chassis alloy ofAl—Mg—Si is coated with a ceramic coating of MgO—Al₂O₃—SiO₂ or MgAl₂O₄.Similarly Al—Ti—Si—Y type alloy can be oxidized followed by formation orcoating of Al2O3-TiO2-SiO2-Y2O3. Note that Ti—Si—Y is <20% of theoverall content of the metal alloy.

In various embodiments, various surface colors or degrees oftransparency may be achieved with ceramic materials and/or coatings. Inone embodiment, a black ceramic surface is formed over aluminum or analuminum alloy with a 0.1 mol/L NaAlO2 electrolyte system and commercialmicro arc oxidation. The aluminum is first coated with a 100 nm ofcopper, such as using chemical vapor deposition, and then annealed in aninert environment for an hour at a temperature of near the melting pointof the aluminum, such as 650 degrees Celsius, to promote adhesion of thecopper to the aluminum. Then micro arc oxidation is applied to oxidizethe surface, such as with oxidation having a depth of approximately 10micrometers or greater to ensure adequate spectral emissivity. Theamount of copper used for the coating should remain less than 5% byweight of the chassis element. In one embodiment, the coating may beapplied over a sputtered aluminum-based ceramic coating or other typesof ceramics. In an alternative embodiment, the coating adds color to analuminum or other base metal, which is coated by an alumina or otherceramic having a transparent or translucent quality to allow the colorof the coating to show. FIG. 9 depicts one example of a motion impartedto the chassis element 14 during micro arc oxidation with a micro arc76. Rotational motion 78 in combination with longitudinal motion 80provides an elongated circular pattern at the surface of chassis element14.

Coating a chassis of aluminum or magnesium metal and/or alloy with alike-metal ceramic provides increased wear resistance and hardness towhat otherwise tend to relatively soft materials. Desired pigmentationsmay be introduced for durable finishes with a hard outer surface. Forexample, vanadium doped zircon pigments are added with a ceramic mixtureof monoclinic zirconia and silica using sodium fluoride as amineralizer. V+4-ZrSiO₄ pigments can rise to a blue coloration at a lowtemperature, such as 750 degrees Celsius or a more intense blue and eventurquoise blue with a high temperature, such as 1300 degrees Celsius. Avariety of doping schemes provide a transparent ceramic materialsuitable for display protection and touch inputs. For example, certainceramic materials combine when produced in the form of polycrystallinebulk parts a relatively high transmission or electromagnetic radiation,such as transparencies of greater than 70%. Some examples of transparentceramics include MgAl₂O₄, AlON, PLZT, PZ (Fe, Nb, Ti, Nd) O₃, Yag,c-ZRO₂, and Ca₁₀(PO₄)₆(OH)₂. In various embodiments of chassis assembledfrom ceramic chassis elements as set forth herein, such as oxide andnitride ceramics, portions of an assembled chassis will have varyingtransparency, coloration and ductility by applying variations inmanufacture techniques for each chassis element to meet the structural,electromagnetic and aesthetic goals of an information handling system.

Referring now to FIG. 10, a functional block diagram depicts a processfor forming a ceramic over a metal using a dopant to compensate fordifferent coefficients of thermal expansion (CTE). When dissimilarmetals having large differences in CTE values are welded adjacent eachother, cooling after the welding process induces tensile stress in onemetal and compressive stress in the other. Tensile stress can cause hotcracking during welding or cold cracking in service unless the stressesare relieved thermally or mechanically. The risk of metal failure undertensile stress is enhanced at joints that operate at elevatedtemperatures in a cyclic temperature mode. In order to reduce stressbetween metals having different CTE values, a glass seal is bonded orinductively welded at the joint. In the example embodiment depicted byFIG. 10, differences in CTE values for an oxide bonded over a base metalsheet are managed by doping the base metal sheet with at least onedopant that is oxidized with the surface of the base metal sheet.

In the example embodiment depicted by FIG. 10, a low melting pointmetal, such as a metal having a melting point of less than 2000 degreesCelsius, is formed to a chassis element shape 82 and has its surfacecoated with a dopant 84. One example of a low melting point metal isaluminum, which may be doped by a coating of one or more of zinc,indium, tin, manganese and silicon. In alternative embodiments,alternative metals of varying melting points and alternative dopants maybe used, such as:

Metallic material Metal surface alloy/coating dOxide/dmetal Al Zn, In,Sn, Mn, Si 1.38 +− 20% Tl V, Nb, Gd, Al, Ni, Al, B Ni—Cu Ti, Li, Al  1.6+− 20% Cast Iron-Grphatized Se, Ni Hi Stregth low alloy steel Se, Ni, CrZn All, In, Sn, Ga, Ti 1.44 +− 20%

Dopants for an underlying metal are selected so that density of theoxide formed over the base metal (dOxide) is higher than the density ofthe base metal (dMetal). Once the surface of chassis element 82 iscoated with the desired dopant metal or metals 84, chassis element isannealed at a temperature substantially near 80% of the melting point ofthe base metal. Annealing is performed in an inert environment to obtainbonding between the underlying metal and dopant with the dopant having athickness of between 5 and 10% of the thickness of the underlying metal.After annealing, oxidation is performed as described above to have theoxide coating 86 over the metal surface with a greater density than theunderlying metal.

Referring now to FIG. 11, an example is depicted of a polymer frame 90ladapted to mount a ceramic plate for use in an information handlingsystem. For example, ceramic plate is a top lid of a laptop informationhandling system or the bottom surface of a tablet information handlingsystem. In one example embodiment, mounting frame 90 is a polymer thatis bonded to ceramic plate. Although a variety of bonding techniques maybe used, one technique for integration of ceramic plate 88 with mountingframe 90 is melting the separate pieces together to establish a bond.Mounting frame 90 is a polymer composite having a material compatiblewith ceramic plate 88. For instance, mounting frame 90 has alumina(Al2O3) or titania (TiO2) in polystyrene (PS) and poly methylmethacrylate (PMMA) matrixes. Greater than 50% loading of ceramicflakes, powder or fibers can increase the strength of polymer frame.Similar high strength commercial polymer like Lexan can also be used atvarious transparency levels. While one component oxide is preferred,note that similar density oxide can be loaded. Ceramic plate 88 isplaced into position of mount frame 90 and then heated to melt theseparate pieces into a contiguous piece for use as an informationhandling system chassis. Ceramic plate 88 may be formed completely as aceramic piece, such as with injection molding and sintering, or as abase metal having a ceramic coating.

Although the present invention has been described in detail, it shouldbe understood that various changes, substitutions and alterations can bemade hereto without departing from the spirit and scope of the inventionas defined by the appended claims.

1-8. (canceled)
 9. An information handling system comprising: aprocessor operable to process information; memory interfaced with theprocessor and operable to store the information; and a chassis, theprocessor and memory contained in the chassis, the chassis having atleast one ceramic chassis element comprising a sheet of a first metalhaving an oxidized outer surface and a ceramic oxide of the first metaldisposed over the oxidized outer surface.
 10. The information handlingsystem of claim 9 wherein the first metal comprises aluminum and theceramic oxide comprises Al₂O₃.
 11. The information handling system ofclaim 10 wherein the ceramic oxide further comprises SiC.
 12. Theinformation handling system of claim 10 wherein the first metalcomprises titanium and the ceramic oxide further comprises TiO₂.
 13. Theinformation handling system of claim 9 wherein the first metal comprisesmagnesium and the ceramic oxide comprises MgO.
 14. The informationhandling system of claim 14 wherein the ceramic oxide further comprisesSiO.
 15. The information handling system of claim 14 wherein the ceramicoxide further comprises Al₂O₃—SiO₂.
 16. The information handling systemof claim 9 further comprising a dopant metal disposed over the firstmetal.
 17. The information handling system of claim 16 wherein thedensity of the oxide formed over the dopant is greater than the densityof the metal. 18-25. (canceled)
 26. The information handling system ofclaim 9 further comprising copper disposed over the ceramic chassiselement, the copper treated with microarc oxidation of sodium aluminumoxide.
 27. The information handling system of claim 26 wherein theceramic chassis element is rotated during the microarc oxidation ofsodium oxide to provide a rotational pattern.
 28. The informationhandling system of claim 26 wherein the copper thickness comprises lessthan 5 per cent of the ceramic chassis element weight.